human_time_diff() localization

Description

Using human_time_diff() function for different purposes, there is big localization problem for example for Czech.

We can use this function in two ways:

1) "Post is 5 days old." - "5 days" (EN) = "5 dní" (CZ)

2) "Post was published 5 days ago." - "5 days" (EN) = "5 dny" (CZ)

English language has only one phrase, but Czech (and others) are much more complicated. For example, WordPress uses this function for list of posts in administration (5 days ago). But new bbPress plugin uses this function for Freshness (that means 5 days). And in this case it is nonsense in Czech language...

SergeyBiryukov: Yes, it would be partial solution, but it is not possible to change "5 days" to "5 days ago" in bbPress and so translation is nonsense even if I change "Freshness". I will try to use ngettext hook to change it (I am not sure if it can be done conditionally only for bbPress plugin?).

But generally, it would be helpfull to have for example optional parameter (or something else) to use human_time_diff() in different ways. It is not always possible to change meaning in which it is used in different plugins (or use ngettext filter). There are two common meanings (old and ago) which should be probably handled differently...

I tried bbPress filters, but using filter bbp_get_topic_freshness_link is only for topics and not for forums and there are also other filters, for example bbp_get_forum_freshness_link (for forum), etc. Digging deeper I found also function (and filter) bbp_get_time_since, but this filter does not work for me, maybe because there is hardcoded function in apply_filters()?